What are the techniques for pressing effervescent tablets?

The pressing of effervescent tablets requires mastering various techniques to ensure the quality and performance of the product. The following will provide a detailed introduction from the stages of raw material processing, granulation, and tablet pressing:

Raw material processing

Particle size control of raw materials: The particle size of raw materials has a significant impact on the compression and performance of effervescent tablets. Generally speaking, the particle size of active ingredients, acid-base foaming agents, and fillers should be moderate and uniform. For example, if the particle size of sodium bicarbonate is too coarse, it may lead to uneven effervescent reaction; If it is too fine, it may affect the flowability of the particles, so it is usually more suitable to grind it to 80-100 mesh. Moisture content of raw materials: The moisture content of raw materials should be strictly controlled. Excessive moisture can cause the particles to become sticky, affecting the smooth progress of tablet pressing, and may also lead to premature reaction of acid-base foaming agents, reducing the effervescent effect; Insufficient moisture content, poor plasticity of particles, and poor hardness and formability of tablets. The moisture content of general raw materials should be controlled at 3% -5%.

Granulation

Adhesive selection and dosage: The type and dosage of adhesive directly affect the quality of particles. For effervescent tablets with good water solubility, an ethanol solution of polyvinylpyrrolidone (PVP) can be used as the adhesive, and its dosage is generally 5% -10% of the total amount of raw materials. If the dosage is too small, the particles are difficult to form; Excessive dosage can make the particles too hard, affecting the dissolution rate of effervescent tablets. Granulation temperature and time: The control of temperature and time is crucial in the drying process of wet granulation. Excessive temperature and time may cause the decomposition of acid-base foaming agents or the failure of active ingredients; If the temperature is too low and the time is too short, the particles will not dry sufficiently, resulting in excessive moisture residue. The drying temperature is usually controlled at 40-60 ℃, and the drying time is 2-4 hours, which needs to be adjusted according to the material characteristics and equipment conditions.

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Mixing order: A reasonable mixing order helps ensure that each component is mixed evenly. Generally, the active ingredient is first mixed with some fillers, then mixed with acid-base foaming agents, and finally added with lubricants and other auxiliary materials. For example, first mix vitamin C with some mannitol evenly, then add citric acid and sodium bicarbonate, and finally add magnesium stearate. This can avoid premature contact reaction of acid-base foaming agents and ensure thorough mixing of all components. Mixing time and speed: If the mixing time is too short, the components will be mixed unevenly; Mixing for too long may cause particle breakage or delamination. The mixing speed should not be too fast, otherwise static electricity may be generated, affecting the mixing effect. The mixing time is usually controlled at 10-20 minutes, and the mixing speed is adjusted according to the type of mixing equipment and the amount of material to achieve the best mixing effect.

Tablet pressing

Pressure control: Pressure is a key factor affecting the quality of effervescent tablets. Excessive pressure, hard effervescent tablets, slow dissolution rate, and possible cracking during storage; Too little pressure, loose effervescent tablets, insufficient hardness, and easy breakage. Generally speaking, for effervescent tablets with a diameter of about 10mm, the pressure of a single stamping press can be controlled within 5-10kN, and the pressure of a rotary tablet press can be adjusted within an appropriate range according to specific equipment and process requirements. Die selection: The shape, size, and surface quality of the die have an impact on the appearance and quality of the effervescent tablets. Choose a suitable punching die based on the shape and specifications of the effervescent tablets, such as circular, elliptical, etc. The surface of the die should be smooth, without wear and scratches, to avoid affecting the demolding and appearance quality of the effervescent sheet. Compression environment control: The temperature and humidity of the compression environment have a significant impact on the compression of effervescent tablets. The general temperature is controlled at 18-25 ℃, and the relative humidity is controlled at 40% -60%. In high humidity environments, effervescent tablets are prone to moisture absorption, leading to sticky particles, difficulty in compression, and decreased effervescent performance; In low humidity environments, particles may generate static electricity, affecting their fluidity and mixing uniformity.